It has been shown in several studies that joint management of different radio access technologies, such as multi-radio resource management (MRRM) can bring substantial gain to network capacity and user performance in a multi-access network. Generally, implementation of MRRM optimizes the usage of resources and minimizes the costs. However, such MRRM algorithms require access specific knowledge, e.g. the capacity and load in different radio cells belonging to different access technologies, and the link characteristics and quality for different access links of a user. For this reason, most MRRM studies suggest an architecture, where (one or more) MRRM functions collect all required access resource information of the different access technologies to determine the best allocation of users to access technologies. From that perspective, multi-access is achieved by connecting multiple different access networks to a common multi-access network.
In most standardisation activities the approach of multi-access integration differs from the previous described approach. There, it is instead assumed that different access networks remain independent and are connected to a common core network.
An exception is the concept of Common Radio Resource Management (CRRM) inter-system handover between the GSM/EDGE Radio Access Network (GERAN) and the Universal Terrestrial Radio Access Network (UTRAN) discussed and partly specified by the third Generation Partnership Project (3GPP).
In the prior art all access specific knowledge is supposed to remain within each access network and the core network is supposed to stay agnostic of any radio- or access specific knowledge, or load information on individual cell level is handled in a CRRM server that is shared between two radio access networks, which is one of the solutions discussed in 3GPP.
There are several reasons for keeping the core network agnostic to access-level information. One is, for example, the problem of scalability if access knowledge on cell level, or even at finer granularity, would be exported into the core network. Another reason is that use of the core network may be extended to new access technologies, as it does not need to be aware of access technology specifics. A further reason is that the core network may belong to another operator (administrative domain), whereby access specific information is not desired to be exposed to the core network. Consequently, the gains of MRRM cannot be easily achieved in an approach combining different access technologies in the core network.